VMware + NetApp Thin on Thin?

[KapsZ28]

I heard that you should never create a Thin NetApp LUN and then a Thin vmdk file on that same LUN. Reason being is that the vmdk file will be fragmented, and the NetApp LUN will also be fragmented causing performance issues. Is this correct?

I read that the main downside to thin on thin is the possibility to oversubscribing if you don't closely monitor your storage, but didn't really see anything about fragmentation and performance issues, especially with a NetApp.

 

[madrebel]

with CoW filesystems the fragmentation argument is moot IMO. unless you're for some reason provisioning an aggregate as a LUN then the LUN is just a .... welll its a logical unit. it doesnt physically tie back to sectors directly.

meaning, if you make an eager zero vmdk once deployed and in prod the amount of fragmentation (of the underlying wafl) shouldn't be any different in either scenario presuming the underlying aggregates are consistent in both examples.

thin on thin does become an issue as you near your usable capacity limitations. not really anything to be super concerned about as the unfucking of this problem is the same as many other storage problems.

buy more and move shit to it.